archive_read: make ARCHIVE_FATAL sticky in data-reading entry points

archive_read: make ARCHIVE_FATAL sticky in data-reading entry points

Three entry points in archive_read.c could return ARCHIVE_FATAL from
the format layer without setting a->archive.state = ARCHIVE_STATE_FATAL,
so subsequent API calls would not see the archive as fatally broken:

- archive_read_data_skip() unconditionally reset state to HEADER even
  when the format's skip returned ARCHIVE_FATAL.

- archive_seek_data() and _archive_read_data_block() forwarded FATAL
  from the format layer without recording it in the archive state.

Fix all three so that ARCHIVE_FATAL causes the state to become
ARCHIVE_STATE_FATAL, consistent with the existing behavior of
archive_read_next_header().